Viscous-Dominated Flow Experiments for Hydrogen Storage in Saline Aquifers

Abstract A multi-phase flow experimental setup is introduced to examine the behavior of H2 transport in a brine-saturated core under different flow rates and flow regimes in the context of underground hydrogen storage (UHS). Analog fluids of decane and viscosified brine were used in lieu of H2 to obtain a viscosity ratio similar to H2-brine flow at reservoir conditions. A normalized finger width was introduced to allow for comparison of finger widths between this analog system and a H2-brine system. X-ray computed tomography (CT) was used to image the flow during decane injection and compute average decane saturation across the core sample, as well as measure fingers that formed during the experiments. The 1D decane saturation profile for the fast-flowing experiment showed initially stable displacement before the onset of viscous fingering, and the profile for the slow-flowing experiment showed the presence of distinct viscous fingers from the onset of injection, to the limits of imaging. The resulting images of the flow tests confirm that viscous fingering is present in both tests, but limitations in equipment capability suggest that there exists a minimum finger width that can be observed with the current setup. This necessitates additional tests at different flow rates to determine the evolution of H2 fingers, as well as determine the minimum finger width observable.